/* ================================================
   CSS Design System - SIer LP
   Theme: Digital Trust & Speed
   Main Color: Orange (#F26522)
   Base: Dark Navy + Gray
   ================================================ */

/* ---------- CSS Custom Properties ---------- */
:root {
  /* Colors */
  --c-primary: #F26522;
  --c-primary-light: #FF8A50;
  --c-primary-dark: #D45518;
  --c-primary-glow: rgba(242, 101, 34, 0.25);

  --c-dark-900: #0B0F1A;
  --c-dark-800: #111827;
  --c-dark-700: #1A2035;
  --c-dark-600: #243049;
  --c-dark-500: #2E3D5F;

  --c-gray-100: #F3F4F6;
  --c-gray-200: #E5E7EB;
  --c-gray-300: #D1D5DB;
  --c-gray-400: #9CA3AF;
  --c-gray-500: #6B7280;
  --c-gray-600: #4B5563;

  --c-white: #FFFFFF;
  --c-success: #10B981;
  --c-error: #EF4444;

  /* Typography */
  --ff-en: 'Inter', sans-serif;
  --ff-ja: 'Noto Sans JP', sans-serif;

  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-md: 1.125rem;
  --fs-lg: 1.25rem;
  --fs-xl: 1.5rem;
  --fs-2xl: 2rem;
  --fs-3xl: 2.5rem;
  --fs-4xl: 3rem;
  --fs-5xl: 3.5rem;

  --fw-light: 300;
  --fw-regular: 400;
  --fw-medium: 500;
  --fw-semibold: 600;
  --fw-bold: 700;
  --fw-extrabold: 800;

  /* Spacing */
  --sp-xs: 0.25rem;
  --sp-sm: 0.5rem;
  --sp-md: 1rem;
  --sp-lg: 1.5rem;
  --sp-xl: 2rem;
  --sp-2xl: 3rem;
  --sp-3xl: 4rem;
  --sp-4xl: 6rem;
  --sp-5xl: 8rem;

  /* Borders & Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;

  --border-subtle: 1px solid rgba(255,255,255,0.06);
  --border-accent: 1px solid rgba(242,101,34,0.3);

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.4);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.5);
  --shadow-glow: 0 0 40px rgba(242,101,34,0.15);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;
  --transition-smooth: 600ms cubic-bezier(0.16, 1, 0.3, 1);

  /* Layout */
  --header-height: 72px;
  --container-max: 1200px;
  --container-padding: 1.5rem;
}

/* ---------- Reset & Base ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--ff-ja);
  font-size: var(--fs-base);
  font-weight: var(--fw-regular);
  line-height: 1.8;
  color: var(--c-gray-200);
  background-color: var(--c-dark-900);
  overflow-x: hidden;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--c-primary);
  text-decoration: none;
  transition: color var(--transition-base);
}

a:hover {
  color: var(--c-primary-light);
}

ul {
  list-style: none;
}

/* ---------- Utility ---------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.sp-only {
  display: none;
}

.text-accent {
  color: var(--c-primary);
}

/* ---------- Fade-in Animation ---------- */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1),
              transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
}

.fade-in.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered children */
.fade-in:nth-child(2) { transition-delay: 0.1s; }
.fade-in:nth-child(3) { transition-delay: 0.2s; }
.fade-in:nth-child(4) { transition-delay: 0.3s; }

/* ================================================
   HEADER
   ================================================ */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  z-index: 1000;
  background: rgba(11, 15, 26, 0.8);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: var(--border-subtle);
  transition: background var(--transition-base), box-shadow var(--transition-base);
}

.header--scrolled {
  background: rgba(11, 15, 26, 0.95);
  box-shadow: var(--shadow-md);
}

.header__nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.header__logo {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  color: var(--c-white);
  font-family: var(--ff-en);
  font-weight: var(--fw-bold);
  font-size: var(--fs-lg);
  text-decoration: none;
}

.header__logo:hover {
  color: var(--c-white);
}

.header__logo-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--c-primary), var(--c-primary-dark));
  color: var(--c-white);
}

.header__logo-icon svg {
  width: 20px;
  height: 20px;
}

.header__menu {
  display: flex;
  align-items: center;
  gap: var(--sp-xs);
}

.header__link {
  display: block;
  padding: var(--sp-sm) var(--sp-md);
  color: var(--c-gray-300);
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  border-radius: var(--radius-md);
  transition: color var(--transition-base), background var(--transition-base);
}

.header__link:hover {
  color: var(--c-white);
  background: rgba(255,255,255,0.05);
}

.header__link--cta {
  background: var(--c-primary);
  color: var(--c-white) !important;
  font-weight: var(--fw-semibold);
  margin-left: var(--sp-sm);
}

.header__link--cta:hover {
  background: var(--c-primary-light);
}

.header__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--sp-sm);
  z-index: 1001;
}

.header__hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--c-white);
  border-radius: 2px;
  transition: transform var(--transition-base), opacity var(--transition-base);
}

.header__hamburger.is-active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.header__hamburger.is-active span:nth-child(2) {
  opacity: 0;
}

.header__hamburger.is-active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ================================================
   SECTION: MV (Main Visual)
   ================================================ */
.mv {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  background: linear-gradient(135deg, var(--c-dark-900) 0%, var(--c-dark-800) 50%, var(--c-dark-700) 100%);
}

.mv__canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
}

.mv__overlay {
  position: absolute;
  inset: 0;
  z-index: 2;
  background: radial-gradient(ellipse at 30% 50%, rgba(242, 101, 34, 0.08) 0%, transparent 60%),
              radial-gradient(ellipse at 70% 50%, rgba(30, 64, 175, 0.06) 0%, transparent 60%);
}

.mv__content {
  position: relative;
  z-index: 3;
  text-align: center;
  padding: calc(var(--header-height) + var(--sp-3xl)) var(--container-padding) var(--sp-3xl);
}

.mv__sub {
  font-family: var(--ff-en);
  font-size: var(--fs-sm);
  font-weight: var(--fw-semibold);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--c-primary);
  margin-bottom: var(--sp-lg);
  opacity: 0;
  animation: fadeUp 0.8s 0.3s forwards;
}

.mv__title {
  font-size: clamp(var(--fs-2xl), 5vw, var(--fs-5xl));
  font-weight: var(--fw-extrabold);
  line-height: 1.3;
  color: var(--c-white);
  margin-bottom: var(--sp-xl);
  opacity: 0;
  animation: fadeUp 0.8s 0.5s forwards;
}

.mv__title--accent {
  color: var(--c-primary);
  background: linear-gradient(135deg, var(--c-primary), var(--c-primary-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.mv__desc {
  font-size: clamp(var(--fs-base), 2vw, var(--fs-lg));
  color: var(--c-gray-300);
  line-height: 1.9;
  margin-bottom: var(--sp-2xl);
  opacity: 0;
  animation: fadeUp 0.8s 0.7s forwards;
}

.mv__desc strong {
  color: var(--c-white);
  font-weight: var(--fw-semibold);
}

.mv__actions {
  display: flex;
  gap: var(--sp-md);
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: var(--sp-2xl);
  opacity: 0;
  animation: fadeUp 0.8s 0.9s forwards;
}

.mv__badges {
  display: flex;
  gap: var(--sp-lg);
  justify-content: center;
  flex-wrap: wrap;
  opacity: 0;
  animation: fadeUp 0.8s 1.1s forwards;
}

.mv__badge {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  padding: var(--sp-sm) var(--sp-md);
  background: rgba(255,255,255,0.04);
  border: var(--border-subtle);
  border-radius: var(--radius-full);
  font-size: var(--fs-sm);
  color: var(--c-gray-300);
}

.mv__badge svg {
  width: 16px;
  height: 16px;
  color: var(--c-primary);
}

.mv__scroll-indicator {
  position: absolute;
  bottom: var(--sp-xl);
  left: 50%;
  transform: translateX(-50%);
  z-index: 3;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-sm);
  opacity: 0;
  animation: fadeUp 0.8s 1.5s forwards;
}

.mv__scroll-indicator span {
  font-family: var(--ff-en);
  font-size: var(--fs-xs);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--c-gray-400);
}

.mv__scroll-line {
  width: 1px;
  height: 40px;
  background: linear-gradient(to bottom, var(--c-primary), transparent);
  animation: scrollLine 2s ease-in-out infinite;
}

@keyframes scrollLine {
  0%, 100% { opacity: 0.3; transform: scaleY(0.5); }
  50% { opacity: 1; transform: scaleY(1); }
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ================================================
   BUTTONS
   ================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-sm);
  padding: 0.75rem 1.75rem;
  font-family: var(--ff-ja);
  font-size: var(--fs-sm);
  font-weight: var(--fw-semibold);
  border-radius: var(--radius-lg);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  white-space: nowrap;
}

.btn svg {
  width: 18px;
  height: 18px;
}

.btn--primary {
  background: linear-gradient(135deg, var(--c-primary), var(--c-primary-dark));
  color: var(--c-white);
  border-color: var(--c-primary);
  box-shadow: 0 4px 14px rgba(242, 101, 34, 0.3);
}

.btn--primary:hover {
  background: linear-gradient(135deg, var(--c-primary-light), var(--c-primary));
  box-shadow: 0 6px 20px rgba(242, 101, 34, 0.45);
  transform: translateY(-2px);
  color: var(--c-white);
}

.btn--outline {
  background: transparent;
  color: var(--c-white);
  border-color: rgba(255,255,255,0.2);
}

.btn--outline:hover {
  background: rgba(255,255,255,0.05);
  border-color: rgba(255,255,255,0.4);
  color: var(--c-white);
  transform: translateY(-2px);
}

.btn--lg {
  padding: 1rem 2.25rem;
  font-size: var(--fs-base);
}

.btn--full {
  width: 100%;
  max-width: 400px;
}

/* ================================================
   SECTION HEADER (shared)
   ================================================ */
.section-header {
  text-align: center;
  margin-bottom: var(--sp-3xl);
}

.section-header__label {
  display: inline-block;
  font-family: var(--ff-en);
  font-size: var(--fs-xs);
  font-weight: var(--fw-bold);
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--c-primary);
  padding: var(--sp-xs) var(--sp-md);
  border: 1px solid rgba(242,101,34,0.3);
  border-radius: var(--radius-full);
  margin-bottom: var(--sp-md);
}

.section-header__title {
  font-size: clamp(var(--fs-xl), 4vw, var(--fs-3xl));
  font-weight: var(--fw-bold);
  color: var(--c-white);
  line-height: 1.4;
  margin-bottom: var(--sp-md);
}

.section-header__desc {
  font-size: var(--fs-base);
  color: var(--c-gray-400);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.8;
}

/* ================================================
   SECTION 2: 課題提起
   ================================================ */
.problems {
  padding: var(--sp-5xl) 0;
  background: var(--c-dark-800);
  position: relative;
}

.problems::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(242,101,34,0.3), transparent);
}

.problems__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--sp-xl);
}

.problem-card {
  background: var(--c-dark-700);
  border: var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: var(--sp-2xl) var(--sp-xl);
  text-align: center;
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth), border-color var(--transition-smooth);
}

.problem-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-glow);
  border-color: rgba(242,101,34,0.3);
}

.problem-card__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 64px;
  height: 64px;
  margin: 0 auto var(--sp-lg);
  background: rgba(242,101,34,0.1);
  border-radius: var(--radius-lg);
  color: var(--c-primary);
}

.problem-card__icon svg {
  width: 28px;
  height: 28px;
}

.problem-card__title {
  font-size: var(--fs-md);
  font-weight: var(--fw-bold);
  color: var(--c-white);
  margin-bottom: var(--sp-md);
  line-height: 1.6;
}

.problem-card__desc {
  font-size: var(--fs-sm);
  color: var(--c-gray-400);
  line-height: 1.8;
}

/* ================================================
   SECTION 3: 解決策
   ================================================ */
.solution {
  padding: var(--sp-5xl) 0;
  background: var(--c-dark-900);
  position: relative;
}

.solution__flow {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: var(--sp-md);
}

.flow-step {
  flex: 1;
  max-width: 240px;
  text-align: center;
  padding: var(--sp-xl);
  background: var(--c-dark-700);
  border: var(--border-subtle);
  border-radius: var(--radius-xl);
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth);
}

.flow-step:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}

.flow-step__number {
  font-family: var(--ff-en);
  font-size: var(--fs-3xl);
  font-weight: var(--fw-extrabold);
  color: rgba(242,101,34,0.15);
  line-height: 1;
  margin-bottom: var(--sp-sm);
}

.flow-step__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  margin: 0 auto var(--sp-md);
  background: linear-gradient(135deg, rgba(242,101,34,0.15), rgba(242,101,34,0.05));
  border-radius: var(--radius-lg);
  color: var(--c-primary);
}

.flow-step__icon svg {
  width: 24px;
  height: 24px;
}

.flow-step__title {
  font-size: var(--fs-base);
  font-weight: var(--fw-bold);
  color: var(--c-white);
  margin-bottom: var(--sp-sm);
}

.flow-step__desc {
  font-size: var(--fs-sm);
  color: var(--c-gray-400);
  line-height: 1.7;
}

.flow-step__arrow {
  display: flex;
  align-items: center;
  padding-top: 80px;
  color: var(--c-primary);
  opacity: 0.4;
}

.flow-step__arrow svg {
  width: 24px;
  height: 24px;
}

/* ================================================
   SECTION 4: 技術スタック
   ================================================ */
.techstack {
  padding: var(--sp-5xl) 0;
  background: var(--c-dark-800);
  position: relative;
}

.techstack::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(242,101,34,0.3), transparent);
}

.techstack__categories {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--sp-xl);
}

.tech-category {
  background: var(--c-dark-700);
  border: var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: var(--sp-xl);
  transition: border-color var(--transition-smooth);
}

.tech-category:hover {
  border-color: rgba(242,101,34,0.2);
}

.tech-category__title {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  font-family: var(--ff-en);
  font-size: var(--fs-base);
  font-weight: var(--fw-bold);
  color: var(--c-white);
  margin-bottom: var(--sp-lg);
  padding-bottom: var(--sp-md);
  border-bottom: var(--border-subtle);
}

.tech-category__title svg {
  width: 20px;
  height: 20px;
  color: var(--c-primary);
}

.tech-category__items {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--sp-md);
}

.tech-item {
  display: flex;
  align-items: center;
  gap: var(--sp-md);
  padding: var(--sp-md);
  background: rgba(255,255,255,0.02);
  border-radius: var(--radius-md);
  transition: background var(--transition-base);
}

.tech-item:hover {
  background: rgba(255,255,255,0.05);
}

.tech-item__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  flex-shrink: 0;
  color: var(--c-primary);
}

.tech-item__icon svg {
  width: 24px;
  height: 24px;
}

.tech-item__name {
  font-size: var(--fs-sm);
  font-weight: var(--fw-medium);
  color: var(--c-gray-200);
}

/* ================================================
   SECTION 5: 開発実績
   ================================================ */
.works {
  padding: var(--sp-5xl) 0;
  background: var(--c-dark-900);
}

.works__grid {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3xl);
}

.work-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-2xl);
  align-items: center;
  background: var(--c-dark-700);
  border: var(--border-subtle);
  border-radius: var(--radius-2xl);
  padding: var(--sp-2xl);
  transition: border-color var(--transition-smooth), box-shadow var(--transition-smooth);
}

.work-card:hover {
  border-color: rgba(242,101,34,0.2);
  box-shadow: var(--shadow-lg);
}

.work-card:nth-child(even) {
  direction: rtl;
}

.work-card:nth-child(even) > * {
  direction: ltr;
}

/* Mockup Displays */
.work-card__visual {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--sp-xl);
}

/* Browser Mockup */
.mockup-browser {
  width: 100%;
  max-width: 400px;
  background: var(--c-dark-600);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-xl);
}

.mockup-browser__bar {
  display: flex;
  gap: 6px;
  padding: 10px 14px;
  background: var(--c-dark-500);
}

.mockup-browser__bar span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--c-dark-700);
}

.mockup-browser__bar span:nth-child(1) { background: #FF605C; }
.mockup-browser__bar span:nth-child(2) { background: #FFBD44; }
.mockup-browser__bar span:nth-child(3) { background: #00CA4E; }

.mockup-browser__content {
  display: flex;
  min-height: 200px;
}

.mockup-sidebar {
  width: 60px;
  background: var(--c-dark-500);
  flex-shrink: 0;
}

.mockup-main {
  flex: 1;
  padding: var(--sp-md);
  display: flex;
  flex-direction: column;
  gap: var(--sp-md);
}

.mockup-chart {
  height: 80px;
  background: linear-gradient(135deg, rgba(242,101,34,0.2), rgba(242,101,34,0.05));
  border-radius: var(--radius-sm);
  position: relative;
  overflow: hidden;
}

.mockup-chart::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 60%;
  background: linear-gradient(to right, 
    transparent 0%, rgba(242,101,34,0.4) 15%, rgba(242,101,34,0.2) 30%, 
    rgba(242,101,34,0.5) 45%, rgba(242,101,34,0.3) 60%, rgba(242,101,34,0.6) 75%, 
    rgba(242,101,34,0.4) 90%, rgba(242,101,34,0.3) 100%);
  clip-path: polygon(0 80%, 10% 60%, 20% 70%, 35% 30%, 50% 50%, 65% 20%, 80% 40%, 100% 10%, 100% 100%, 0 100%);
}

.mockup-cards {
  display: flex;
  gap: var(--sp-sm);
}

.mockup-card-sm {
  flex: 1;
  height: 50px;
  background: var(--c-dark-500);
  border-radius: var(--radius-sm);
}

/* Table mockup */
.mockup-table {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: var(--sp-sm);
}

.mockup-row {
  height: 28px;
  background: var(--c-dark-500);
  border-radius: var(--radius-sm);
}

.mockup-row:first-child {
  background: rgba(242,101,34,0.2);
}

/* Phone Mockup */
.mockup-phone {
  width: 180px;
  background: var(--c-dark-600);
  border-radius: 24px;
  padding: 8px;
  box-shadow: var(--shadow-xl);
  margin: 0 auto;
}

.mockup-phone__notch {
  width: 60px;
  height: 20px;
  background: var(--c-dark-900);
  border-radius: 0 0 12px 12px;
  margin: 0 auto var(--sp-sm);
}

.mockup-phone__content {
  background: var(--c-dark-500);
  border-radius: 16px;
  padding: var(--sp-md);
  min-height: 280px;
  display: flex;
  flex-direction: column;
  gap: var(--sp-sm);
}

.mockup-phone__header {
  height: 24px;
  background: rgba(242,101,34,0.2);
  border-radius: var(--radius-sm);
}

.mockup-phone__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-sm);
  flex: 1;
}

.mockup-phone__item {
  background: var(--c-dark-600);
  border-radius: var(--radius-sm);
  min-height: 70px;
}

.mockup-phone__nav {
  height: 32px;
  background: var(--c-dark-700);
  border-radius: var(--radius-sm);
}

/* Work Card Body */
.work-card__tags {
  display: flex;
  gap: var(--sp-sm);
  flex-wrap: wrap;
  margin-bottom: var(--sp-md);
}

.tag {
  display: inline-block;
  padding: 2px 10px;
  font-family: var(--ff-en);
  font-size: var(--fs-xs);
  font-weight: var(--fw-semibold);
  color: var(--c-primary);
  background: rgba(242,101,34,0.1);
  border: 1px solid rgba(242,101,34,0.2);
  border-radius: var(--radius-full);
}

.work-card__title {
  font-size: var(--fs-xl);
  font-weight: var(--fw-bold);
  color: var(--c-white);
  margin-bottom: var(--sp-md);
}

.work-card__desc {
  font-size: var(--fs-sm);
  color: var(--c-gray-400);
  line-height: 1.8;
  margin-bottom: var(--sp-lg);
}

.work-card__meta {
  display: flex;
  gap: var(--sp-xl);
}

.work-card__meta div {
  display: flex;
  gap: var(--sp-sm);
}

.work-card__meta dt {
  font-size: var(--fs-xs);
  color: var(--c-gray-500);
  font-weight: var(--fw-medium);
}

.work-card__meta dd {
  font-size: var(--fs-xs);
  color: var(--c-gray-200);
  font-weight: var(--fw-semibold);
}

/* ================================================
   SECTION 6: 強み
   ================================================ */
.strengths {
  padding: var(--sp-5xl) 0;
  background: var(--c-dark-800);
  position: relative;
}

.strengths::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(242,101,34,0.3), transparent);
}

.strengths__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--sp-xl);
}

.strength-card {
  position: relative;
  background: var(--c-dark-700);
  border: var(--border-subtle);
  border-radius: var(--radius-xl);
  padding: var(--sp-2xl) var(--sp-xl);
  text-align: center;
  transition: transform var(--transition-smooth), box-shadow var(--transition-smooth), border-color var(--transition-smooth);
  overflow: hidden;
}

.strength-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-glow);
  border-color: rgba(242,101,34,0.3);
}

.strength-card__number {
  position: absolute;
  top: -10px;
  right: 16px;
  font-family: var(--ff-en);
  font-size: 5rem;
  font-weight: var(--fw-extrabold);
  color: rgba(242,101,34,0.06);
  line-height: 1;
  pointer-events: none;
}

.strength-card__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 72px;
  height: 72px;
  margin: 0 auto var(--sp-lg);
  background: linear-gradient(135deg, rgba(242,101,34,0.15), rgba(242,101,34,0.05));
  border-radius: var(--radius-xl);
  color: var(--c-primary);
}

.strength-card__icon svg {
  width: 32px;
  height: 32px;
}

.strength-card__title {
  font-size: var(--fs-lg);
  font-weight: var(--fw-bold);
  color: var(--c-white);
  margin-bottom: var(--sp-md);
}

.strength-card__desc {
  font-size: var(--fs-sm);
  color: var(--c-gray-400);
  line-height: 1.8;
  text-align: left;
}

/* ================================================
   SECTION 7: FAQ
   ================================================ */
.faq {
  padding: var(--sp-5xl) 0;
  background: var(--c-dark-900);
}

.faq__list {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--sp-md);
}

.faq-item {
  background: var(--c-dark-700);
  border: var(--border-subtle);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: border-color var(--transition-base);
}

.faq-item[open] {
  border-color: rgba(242,101,34,0.3);
}

.faq-item__question {
  display: flex;
  align-items: center;
  gap: var(--sp-md);
  padding: var(--sp-lg) var(--sp-xl);
  cursor: pointer;
  list-style: none;
  font-size: var(--fs-base);
  font-weight: var(--fw-semibold);
  color: var(--c-white);
  transition: background var(--transition-base);
}

.faq-item__question::-webkit-details-marker {
  display: none;
}

.faq-item__question:hover {
  background: rgba(255,255,255,0.02);
}

.faq-item__q-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  flex-shrink: 0;
  background: var(--c-primary);
  color: var(--c-white);
  font-family: var(--ff-en);
  font-size: var(--fs-sm);
  font-weight: var(--fw-bold);
  border-radius: var(--radius-md);
}

.faq-item__toggle {
  margin-left: auto;
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  color: var(--c-gray-400);
  transition: transform var(--transition-base);
}

.faq-item[open] .faq-item__toggle {
  transform: rotate(180deg);
}

.faq-item__answer {
  display: flex;
  gap: var(--sp-md);
  padding: 0 var(--sp-xl) var(--sp-lg);
  animation: slideDown 0.3s ease;
}

.faq-item__a-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  flex-shrink: 0;
  background: rgba(242,101,34,0.1);
  color: var(--c-primary);
  font-family: var(--ff-en);
  font-size: var(--fs-sm);
  font-weight: var(--fw-bold);
  border-radius: var(--radius-md);
}

.faq-item__answer p {
  font-size: var(--fs-sm);
  color: var(--c-gray-300);
  line-height: 1.8;
  padding-top: 4px;
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ================================================
   SECTION 8: CTA / Contact
   ================================================ */
.contact {
  padding: var(--sp-5xl) 0;
  background: var(--c-dark-800);
  position: relative;
}

.contact::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(242,101,34,0.3), transparent);
}

.contact-form {
  max-width: 700px;
  margin: 0 auto;
  background: var(--c-dark-700);
  border: var(--border-subtle);
  border-radius: var(--radius-2xl);
  padding: var(--sp-2xl);
}

.contact-form__row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-lg);
}

.form-group {
  margin-bottom: var(--sp-lg);
}

.form-group--checkbox {
  margin-top: var(--sp-sm);
}

.form-label {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  font-size: var(--fs-sm);
  font-weight: var(--fw-semibold);
  color: var(--c-gray-200);
  margin-bottom: var(--sp-sm);
}

.form-label__required {
  font-size: var(--fs-xs);
  color: var(--c-white);
  background: var(--c-primary);
  padding: 1px 6px;
  border-radius: var(--radius-sm);
  font-weight: var(--fw-bold);
}

.form-label__optional {
  font-size: var(--fs-xs);
  color: var(--c-gray-400);
  background: var(--c-dark-500);
  padding: 1px 6px;
  border-radius: var(--radius-sm);
  font-weight: var(--fw-medium);
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  font-family: var(--ff-ja);
  font-size: var(--fs-sm);
  color: var(--c-white);
  background: var(--c-dark-600);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: var(--radius-md);
  outline: none;
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

.form-input::placeholder,
.form-textarea::placeholder {
  color: var(--c-gray-500);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  border-color: var(--c-primary);
  box-shadow: 0 0 0 3px rgba(242,101,34,0.15);
}

.form-input.is-error,
.form-select.is-error,
.form-textarea.is-error {
  border-color: var(--c-error);
  box-shadow: 0 0 0 3px rgba(239,68,68,0.15);
}

.form-select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%239CA3AF' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 1rem center;
  padding-right: 2.5rem;
}

.form-textarea {
  resize: vertical;
  min-height: 120px;
}

.form-error {
  display: block;
  font-size: var(--fs-xs);
  color: var(--c-error);
  margin-top: var(--sp-xs);
  min-height: 1.2em;
}

.form-checkbox {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  cursor: pointer;
  font-size: var(--fs-sm);
  color: var(--c-gray-300);
}

.form-checkbox input[type="checkbox"] {
  display: none;
}

.form-checkbox__mark {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  border: 2px solid rgba(255,255,255,0.2);
  border-radius: var(--radius-sm);
  background: var(--c-dark-600);
  transition: all var(--transition-base);
}

.form-checkbox input:checked + .form-checkbox__mark {
  background: var(--c-primary);
  border-color: var(--c-primary);
}

.form-checkbox input:checked + .form-checkbox__mark::after {
  content: '';
  display: block;
  width: 6px;
  height: 10px;
  border: 2px solid white;
  border-top: none;
  border-left: none;
  transform: rotate(45deg) translateY(-1px);
}

.form-checkbox__text a {
  text-decoration: underline;
}

.contact-form__submit {
  display: flex;
  justify-content: center;
  margin-top: var(--sp-xl);
}

.contact-form__success {
  text-align: center;
  padding: var(--sp-2xl);
  color: var(--c-success);
}

.contact-form__success svg {
  width: 48px;
  height: 48px;
  margin: 0 auto var(--sp-md);
}

.contact-form__success p {
  font-size: var(--fs-base);
  color: var(--c-gray-200);
  line-height: 1.8;
}

/* ================================================
   FOOTER
   ================================================ */
.footer {
  padding: var(--sp-3xl) 0 var(--sp-xl);
  background: var(--c-dark-900);
  border-top: var(--border-subtle);
}

.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: var(--sp-xl);
  border-bottom: var(--border-subtle);
  margin-bottom: var(--sp-xl);
}

.footer__logo {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  color: var(--c-white);
  font-family: var(--ff-en);
  font-weight: var(--fw-bold);
  font-size: var(--fs-lg);
}

.footer__logo:hover {
  color: var(--c-white);
}

.footer__logo svg {
  width: 24px;
  height: 24px;
  color: var(--c-primary);
}

.footer__tagline {
  font-size: var(--fs-sm);
  color: var(--c-gray-500);
  margin-top: var(--sp-sm);
}

.footer__nav {
  display: flex;
  gap: var(--sp-lg);
  flex-wrap: wrap;
}

.footer__nav a {
  font-size: var(--fs-sm);
  color: var(--c-gray-400);
  transition: color var(--transition-base);
}

.footer__nav a:hover {
  color: var(--c-primary);
}

.footer__bottom {
  text-align: center;
}

.footer__bottom small {
  font-size: var(--fs-xs);
  color: var(--c-gray-500);
}

/* ================================================
   RESPONSIVE: Tablet (max-width: 1024px)
   ================================================ */
@media (max-width: 1024px) {
  .problems__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .solution__flow {
    flex-wrap: wrap;
  }

  .flow-step__arrow {
    display: none;
  }

  .flow-step {
    max-width: none;
  }

  .solution__flow {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
  }

  .techstack__categories {
    grid-template-columns: repeat(2, 1fr);
  }

  .work-card {
    grid-template-columns: 1fr;
  }

  .work-card:nth-child(even) {
    direction: ltr;
  }

  .strengths__grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .footer__inner {
    flex-direction: column;
    gap: var(--sp-xl);
    text-align: center;
  }

  .footer__nav {
    justify-content: center;
  }
}

/* ================================================
   RESPONSIVE: Tablet Small (max-width: 768px)
   ================================================ */
@media (max-width: 768px) {
  :root {
    --header-height: 64px;
    --container-padding: 1.25rem;
  }

  .sp-only {
    display: inline;
  }

  /* Header mobile */
  .header__hamburger {
    display: flex;
  }

  .header__menu {
    position: fixed;
    top: 0;
    right: -100%;
    width: 280px;
    height: 100vh;
    flex-direction: column;
    gap: var(--sp-sm);
    padding: calc(var(--header-height) + var(--sp-xl)) var(--sp-xl) var(--sp-xl);
    background: var(--c-dark-800);
    border-left: var(--border-subtle);
    transition: right var(--transition-smooth);
    z-index: 999;
  }

  .header__menu.is-open {
    right: 0;
  }

  .header__link {
    width: 100%;
    font-size: var(--fs-base);
    padding: var(--sp-md);
  }

  .header__link--cta {
    margin-left: 0;
    margin-top: var(--sp-md);
    text-align: center;
  }

  /* Sections */
  .problems__grid {
    grid-template-columns: 1fr;
    gap: var(--sp-md);
  }

  .solution__flow {
    grid-template-columns: 1fr;
  }

  .techstack__categories {
    grid-template-columns: 1fr;
  }

  .strengths__grid {
    grid-template-columns: 1fr;
  }

  .contact-form__row {
    grid-template-columns: 1fr;
    gap: var(--sp-md);
  }

  .contact-form {
    padding: var(--sp-xl);
  }

  .work-card {
    padding: var(--sp-xl);
  }

  .work-card__meta {
    flex-direction: column;
    gap: var(--sp-sm);
  }

  .mv__badges {
    flex-direction: column;
    align-items: center;
  }

  .btn--lg {
    padding: 0.875rem 1.75rem;
    font-size: var(--fs-sm);
  }
}

/* ================================================
   RESPONSIVE: Mobile (max-width: 480px)
   ================================================ */
@media (max-width: 480px) {
  :root {
    --container-padding: 1rem;
  }

  .mv__actions {
    flex-direction: column;
    align-items: center;
  }

  .mv__actions .btn {
    width: 100%;
    max-width: 300px;
  }

  .section-header {
    margin-bottom: var(--sp-2xl);
  }

  .faq-item__question {
    padding: var(--sp-md);
    font-size: var(--fs-sm);
  }

  .faq-item__answer {
    padding: 0 var(--sp-md) var(--sp-md);
  }

  .mockup-phone {
    width: 140px;
  }
}

/* ---------- Accessibility ---------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .fade-in {
    opacity: 1;
    transform: none;
  }
}

:focus-visible {
  outline: 2px solid var(--c-primary);
  outline-offset: 2px;
}